Lower hand guard with heat shield for use with a modular integrated rail system

ABSTRACT

A metal heat shield insert is provided for installation into the lower hand guard of an integrated rail system. The heat shield is received and supported in a pair of opposing mounting channels that are formed on the inside of the lower hand guard. The body of the heat shield includes a plurality of venting holes to permit air to flow through the heat shield. When the heat shield is installed in assembled relation with the hand guard, the venting holes in the heat shield are offset in location from the venting holes in the hand guard to provide an indirect venting arrangement.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is related to and claims priority from earlier filed U.S. Provisional Patent Application No. 60/743,249, filed Feb. 8, 2006, the contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates generally to modular integrated rail assemblies for combat weapons. More specifically the present invention relates to a heat shield for the lower hand guard of the rail system.

As the field of combat and commercial weaponry expands, numerous add-on enhancements have become available for attachment to standard firearms, thereby significantly upgrading the capability of the firearm. Of particular interest in the area of combat weapons is the well-known M16/M4 weapon system (M16 and M4 are trademarks of Colt Defense, Inc.). The M16 has been in service for a number of years and will continue to be a popular rifle both in U.S. and foreign militaries for the foreseeable future. Generally, the M16/M4 weapon 2 includes a lower receiver 4, upper receiver 6, butt stock 8, and barrel 10. (See FIG. 1)

The newer models of the M16/M4 weapons further include a mil-std 1913 dovetail rail 12 extending along the top of the upper receiver. This integrated receiver rail provides a convenient mounting point for many types of enhancement devices such as scopes and other sighting devices. However, space on the upper receiver rail is limited, and many military personnel often have multiple sighting devices that are each tailored to perform in different combat situations. In addition, there are a variety of lighting devices, handgrips, etc. that could also be attached to the weapon for enhanced use of the weapon. The difficulty is that there is simply not enough space on the integrated rail provided on the upper receiver to accommodate all of the desired accessories. Accordingly, the increasing development and refinement of laser sights, infrared lighting, visible lighting, night vision, and specialized scopes and magnifiers, and other accessories continues to drive the need for versatile and reliable integration systems that include additional mil-std 1913 dovetail rails positioned above or around the barrel of the weapon that can support this important equipment and yet stand the test of rugged military use and abuse.

Responding to this need, the applicant has developed a modular integrated rail system (A.R.M.S.® S.I.R.® system), which has been well received by the military and has become popular with several branches of the military (See FIG. 2). The A.R.M.S. S.I.R. system is fully described in U.S. Pat. No. 6,490,822, the entire contents of which are incorporated herein by reference.

These modular integrated rail systems for combat weapons generally include an upper hand guard 14, a clamp 16 for securing the upper hand guard 14 to the weapon 2, a lower firearm accessory 18 (in most cases this is a lower hand guard), various optional rail segments, and in many cases, a sling swivel 20 for attaching a shoulder sling to carry the weapon 10.

The upper hand guard 14 is the main structural element of the system. The upper hand guard is 14 generally semi-cylindrical in shape and has a forward end and a rearward end and a mil-std 1913 dovetail rail extending longitudinally between the forward end and the rearward end. The semi-cylindrical upper hand guard 14 further includes symmetrically opposing side walls that extend outwardly and downwardly from the dovetail rail and terminate in symmetrically opposing longitudinally extending mounting channels. The mounting channels are used to mount various accessories, such as a lower hand guard or a grenade launcher, to the upper hand guard.

A clamp 16 is provided at the rearward end of the upper hand guard 14 to removably secure the upper hand guard 14 to the firearm 2. In the original S.I.R. system as shown in U.S. Pat. No. 6,490,822, the clamp is an elongated clamping rail that secures the upper hand guard to the dovetail rail on the top of the upper receiver of the weapon. In the alternative, the clamp 16 is a U-shaped yoke that secures the upper hand guard 14 to the barrel nut 21 as is depicted in FIG. 26 of the '822 patent and in FIG. 2 in the present application.

As was stated above, the lower firearm accessory can be one of many different types of accessories, but in the context of the present invention comprises a lower hand guard, wherein the lower hand guard includes symmetrically opposing mating formations for removably securing the hand guard to the mounting channels in the upper hand guard. In the preferred embodiments as described herein, the mating formations comprise projections that are slidably received within the mounting channels.

As is well known in the art, the temperature of a gun barrel can quickly rise to 900° F. during repeated firing. This type of heat can damage or destroy attachments that are mounted in direct contact with the barrel. Additionally, the heat generated by the gun barrel is transferred to any devices mounted directly on the barrel, such as other prior art hand guards, thereby resulting in the direct transfer of enough heat to burn a user's hands and to potentially interfere with the operation of other attachments. The existing S.I.R. systems avoid direct thermal contact with the barrel of the weapon by supporting the entire rail system on the upper receiver and/or the barrel nut. In addition, the lower hand guard is molded from a high impact plastic, which is a good thermal insulator. Heat that is transferred from the barrel into the upper receiver must then be transferred into the upper hand guard and then subsequently into the lower hand guard. Since the lower hand guard is plastic, and a good insulator, very little heat is conducted into from the barrel into the hand guard.

While the existing A.R.M.S.® S.I.R. ® system provides improved performance in the category of thermal conductivity, there is still need for improved management of heat that is radiated from the barrel. As is well known in the art, heat is dissipated both by conduction through adjacent bodies, and by radiation to the ambient environment. A significant portion of the heat generated by the gun barrel is dissipated through radiation, and although the hand guard of the S.I.R. system does not conduct any significant amount of heat, it is still in close enough proximity to the barrel that radiant heat from the barrel can be felt on the hands of the operator. In addition, the existing hand guard includes a plurality of venting holes along the length thereof to provide air flow through the hand guard and allow the ambient environment to carry away much of the heat. However, those same venting holes provide a direct path for the radiant transfer of heat directly to the hand of the operator.

There is therefore a need for a lower hand guard assembly for an S.I.R. that effectively prevents the direct transfer of heat from the barrel of the firearm to a user's hands. There is a further need for a heat shielding assembly for use in conjunction with a lower hand guard component that allows adequate air flow around the barrel of the firearm while effectively preventing the direct transfer of heat from the barrel of the firearm to a user's hands. Finally, there is a need for a heat shield for use in conjunction with the lower hand guard component that includes vent holes therein that are offset relative to the vent holes in the lower hand guard thereby effectively preventing the direct transfer of heat from the barrel of the firearm to a user's hands

BRIEF SUMMARY OF THE INVENTION

In this regard, the present invention is directed to a metal heat shield insert that is received into the lower hand guard. The heat shield is received and supported in a pair of opposing mounting channels that are formed on the inside of the lower hand guard. Generally, the heat shield comprises an elongated metal sheet having a curved central body portion, and mounting flanges extending along opposing side edges. The mounting flanges are slidably received into the opposing channels formed in the hand guard to support the heat shield within the interior of the hand guard. The body of the heat shield includes a plurality of venting holes to permit air to flow through the heat shield. It should be noted that when the heat shield is installed in assembled relation with the hand guard, the venting holes in the heat shield are offset in location from the venting holes in the hand guard to provide an indirect venting arrangement as will be described in detail below.

The lower hand guard includes two longitudinally extending opposed mounting channels on the inner surface thereof. These mounting channels frictionally receive the flanges on the sides of the heat shield and support the heat shield in a suspended position between the barrel and the inner surface of the lower hand guard providing insulating air space between the barrel and the heat shield, and between the heat shield and inner surface of the hand guard.

It is therefore an object of the present invention to provide a heat shield assembly that works in connection with the lower hand guard of an S.I.R system to prevent the transfer of heat from the barrel of the firearm to an outer surface of the hand guard. It is a further object of the present invention to provide a heat shield that is integrated into the lower hand guard and includes venting that is not in alignment with the venting of the lower hand guard thereby preventing a direct radiational transfer of heat from the firearm barrel to an outer surface of the hand guard.

These together with other objects of the invention, along with various features of novelty, which characterize the invention, are pointed out with particularity in the claims annexed hereto and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and the specific objects attained by its uses, reference should be had to the accompanying drawings and descriptive matter in which there is illustrated a preferred embodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings which illustrate the best mode presently contemplated for carrying out the present invention:

FIG. 1 is a side view of a prior art firearm;

FIG. 2 is a perspective view of a prior art modular interface system;

FIG. 3 is a perspective view of a modular interface system with the lower hand guard removed;

FIG. 3A is a perspective view of a clamping style modular rail system;

FIG. 4 is a top view of the heat shield of the present invention;

FIG. 5 is a top of the heat shield partially installed into the lower hand guard;

FIG. 6 is a top of the heat shield fully installed into the lower hand guard;

FIG. 7 is a bottom view of the lower hand guard with heat shield installed therein;

FIG. 8 is a cross-sectional view of the lower hand guard with the heat shield installed therein taken along line 8-8 of FIG. 6;

FIG. 9 is a side view of the prior art rail system as shown in FIG. 3A, with the heat shield shown in cross-section.

DETAILED DESCRIPTION OF THE INVENTION

Now referring to the drawings, the heat shield of the present invention system is shown and generally illustrated at FIGS. 4-9. As can be seen, the present invention is directed to a metal heat shield insert 22 that is received into the lower hand guard 18. The heat shield 22 is received and supported in a pair of opposing mounting channels 24 that are formed on the inside of the lower hand guard 18. Generally, the heat shield 22 comprises an elongated metal sheet having a curved central body portion 23, and mounting flanges 26 extending along opposing side edges. The mounting flanges 26 are slidably received into the opposing channels 24 formed in the lower hand guard 18 to support the heat shield 22 within the interior of the lower hand guard 18. The body 23 of the heat shield 22 includes a plurality of venting holes 28 to permit air to flow through the heat shield 22. It should be noted that when the heat shield 22 is installed in assembled relation with the lower hand guard 18, the venting holes 28 in the heat shield 22 are offset in location from the venting holes 30 in the lower hand guard 18 to provide an indirect venting arrangement. Turning to FIGS. 7 and 8 in particular, it can be seen that there is no direct path through both the vent holes 30 in the lower hand guard 18 and the vent holes 28 in the heat shield 22 thereby preventing the direct transfer of radiational heat. With the offset arrangement of the venting holes 28, 30, air can still enter through the vent holes 30 in the lower hand guard 18, flow through the air space 32 between the lower hand guard 18 and the heat shield 22 and then flow upwardly through the vent holes 28 in the heat shield 22 to cool the barrel of the firearm.

The lower hand guard 18 includes two longitudinally extending opposed mounting channels 24 on the inner surface thereof. These mounting channels 24 frictionally receive the flanges 26 on the sides of the heat shield 22 and support the heat shield 22 in a suspended position between the barrel and the inner surface of the lower hand guard 18 providing insulating air space between the barrel and the heat shield 22 and between the heat shield 22 and inner surface of the hand guard 18.

The metal heat shield 22 thus provides at least two additional mechanisms for heat management. First, the metal heat shield 22 acts as a reflector to reflect radiant heat upwardly away from the operator's hands. In this regard, at least a portion of the radiant heat is reflected back upwardly in the direction of the upper hand guard 14. Secondly, the suspended position of the heat shield 22 combined with the offset arrangement of the venting holes 28, 30 in the heat shield 22 and the lower hand guard 18 substantially reduces the direct flow of hot air from within the lower hand guard 18 onto the operator's hands.

Referring to FIG. 6, the heat shield 22 can also be seen to include a detent 34 on the end thereof. The detent 34 is provided so that a user can easily insert a finger between the heat shield 22 and the lower hand guard 18 in order to grip the end of the heat shield 22 for removal from the lower hand guard 18. Accordingly, the detent 34 provides additional clearance and a positive grip for removal of the heat shield 22. In addition, referring to FIG. 9, the detent 34 provides a positive stop wall to prevent movement of the heat shield when the lower hand guard 18 is assembled with the upper hand guard 14. More specifically, it can be seen that the detent 34 positively rests against the forward wall of the clamp 16 of the rail system. This further prevents the vent holes 28 in the heat shield 22 from accidentally moving into alignment with the vent holes 30 in the lower hand guard 18 and insures proper shielding functionality.

Referring back to FIG. 6, the heat shield 22 further includes two tabs 36 extending outwardly from the end thereof straddling the detent 34. The tabs 36 are provided as a mechanism to insure that the heat shield 22 remains in the correct position within the lower hand guard 18 when the lower hand guard 18 is installed onto the S.I.R. system. With the lower hand guard 18 installed onto the S.I.R. system, the tabs 36 extend backwardly skirting just beneath the lower surface of the clamp 16 to sit in closely spaced facing relation with the surface of the clamp 16. As a result, the tabs 36 also serve to retain the heat shield 22 in the proper position.

It can therefore be seen that the present invention provides a unique heat shield insert for use in connection with the lower hand guard of an S.I.R. system. Further, the present invention provides a heat shield that effectively reduces convective transfer of heat into the lower hand guard while also preventing the direct radiational transfer of heat by offsetting the vent holes in the heat shield relative to the vent holes in the lower hand guard. For these reasons, the present invention is believed to represent a significant advancement in the art, which has substantial commercial merit.

While there is shown and described herein certain specific structure embodying the invention, it will be manifest to those skilled in the art that various modifications and rearrangements of the parts may be made without departing from the spirit and scope of the underlying inventive concept and that the same is not limited to the particular forms herein shown and described except insofar as indicated by the scope of the appended claims. 

1. A heat shield for a firearm comprising: an elongated curved central body portion having opposing side edges; mounting flanges extending outwardly from said opposing side edges; and vent holes extending through said body portion; said mounting flanges being configured and arranged to be slidably received into opposing channels in a lower hand guard for said firearm, wherein said lower hand guard includes vent holes, said heat shield vent holes being offset relative to said lower hand guard vent holes when said heat shield is received in said lower hand guard.
 2. The heat shield of claim 1, wherein said heat shield is formed from metal.
 3. The heat shield of claim 1, wherein said central body is in spaced relation an inner surface of said lower hand guard when said mounting flanges are received in said opposing channels defining an air space therebetween.
 4. The heat shield of claim 3, wherein air enters through the vent holes in said lower hand guard, flows through said air gap and passes through said vent holes in said heat shield.
 5. The heat shield of claim 1, further comprising a detent formed on one end of said body portion, said detent creating a gripping surface to allow said heat shield to be removed from said lower hand guard.
 6. The heat shield of claim 1, further comprising at least one tab extending rearwardly from one end of said body portion, said tab configured and arranged to contact a surface on said firearm when said heat shield is installed in said lower hand guard and said lower hand guard is installed on said firearm, said tab preventing said heat shield from sliding rearwardly within said lower hand guard.
 7. A lower accessory for a modular firearm accessory system comprising in combination: a lower hand guard including a peripheral side wall, vent holes formed in said peripheral side wall and opposing channels formed adjacent opposing upper edges of said peripheral side wall; and a heat shield comprising: an elongated curved central body portion having opposing side edges; mounting flanges extending outwardly from said opposing side edges; and vent holes extending through said body portion; said mounting flanges being configured and arranged to be slidably received into opposing channels in said lower hand guard, said heat shield vent holes being offset relative to said lower hand guard vent holes when said heat shield is received in said lower hand guard.
 8. The lower accessory of claim 7, wherein said heat shield is formed from metal.
 9. The lower accessory of claim 7, wherein said central body is in spaced relation an inner surface of said lower hand guard when said mounting flanges are received in said opposing channels defining an air space therebetween.
 10. The lower accessory of claim 9, wherein air enters through the vent holes in said lower hand guard, flows through said air gap and passes through said vent holes in said heat shield.
 11. The lower accessory of claim 7, further comprising a detent formed on one end of said body portion of said heat shield, said detent creating a gripping surface to allow said heat shield to be removed from said lower hand guard.
 12. The lower accessory of claim 7, further comprising at least one tab extending rearwardly from one end of said body portion, said tab configured and arranged to contact a surface on said firearm when said heat shield is installed in said lower hand guard and said lower hand guard is installed on said firearm, said tab preventing said heat shield from sliding rearwardly within said lower hand guard. 